If your vacations do not span a full or even half block, you need to go through a few extra steps to get the vacations to span just the days you want.

There are two ways to do it. Put a block schedule on screen and click on a cell you've entered as a split Vac and other assignment. Open the View menu and select Block width / Day. You'll see the master schedule displayed by day and you can change the extra week (or 3 or 4 days) of Vac to whatever service the person is doing the other half of the month. Go to View / Block width  / Custom to put the block schedule back to your standard month/block view.

The other way to handle vacations is to enter them as special requests. On the block schedule, you'll see special requests as green bars. The position and length of the green bars represent the date and length of the request. Once you've entered a request, you can click on the green bar to convert a request to actual daily assignments. If a person is splitting the month between Vac and ER, for example, you'll want to enter ER for the full month and then convert the special request to assigned days of Vac.

The end result of the two methods is the same. The feature that lets you click on a request flag to convert it to an assignment saves you from having to change the block view to be by day or week and adjust the underlying daily assignments yourself.

For attending schedules - OnCall includes a system to track vacation, CME and sick days.